Balers, particularly roto-balers manufactured at this time, an example of which is described in WO-A1-98/17096, are equipped with take-up devices, so-called pick-ups, that are intended to take up the widest possible swaths in order to attain a high harvesting capacity. So that the take-up device maintains a certain distance from the ground at all times, support wheels are provided on it.
A roto-baler is known from U.S. Pat. No. 4,838,015 in which the position of the take-up device is controlled by the raising and lowering of steering arms of a two-point coupling in the rear region of the agricultural tractor. Particularly in today's high speeds in the baling it appears impossible for an operator to constantly look to the rear during the operation to see whether the take-up device maintains the correct distance from the ground.
EP-A-1 208 738 also discloses a roto-baler, this time, however with sensors that determine the distance between the take-up device and the ground and move the take-up device upward or downward as a function of the distance so determined. In this solution the relative position between the take-up device and a following conveyor rotor or a conveyor channel leading to it changes.
Finally FR-A-2 546 368 discloses a roto-baler in which the entire frame is raised hydraulically by an operator on an agricultural tractor in order to maintain the correct operating height of the take-up device. The take-up device cannot be readjusted with respect to the frame of the baler.
The problem underlying the invention is seen in the fact that material flow problems can occur downstream of the take-up device if the position of the take-up device varies too much due to sudden changes in the height of the ground. This is the result of the fact that the support wheels can change the position of the take-up device while the frame of the baler on which the take-up device is suspended remains in its position. In other cases in which not only the position of the take-up device but also the position of the entire baler is changed, the control is too inexact, particularly since it depends on the attention of an operator.